In the courtyard, take Shao Kahn's Hammer and break the wooden gate by coordinates 3210, 190.
Then turn left, where there will be a weak part of the wall - break it with a hammer and you will find a gong. Interact with him to open the Forge and the achievement.
Craft
To create an item, you need to enter the Forge, which is located on the south side of the courtyard in the Krypt. The recipes can be found in the Collection section of the menu, but if you want the complete recipes, you will need to go through the Tower of Time, the Temple and the entire Crypt.
All recipes for crafting
They are in chests that appear randomly with each new playthrough.
Shinnok's amulet - Enchanted Demon Heart, Necromancer's Eye for crafting, Skeleton Soul
Makana Lynx from Cana's Armory - Copper Plating, Essence of Edenic Magic, Element of Order
Aether Armor - Element of Order, Essence of Edenic Magic
Quai Liang's Frosty Arsenal (Sub-Zero) - Copper plating, Spit Kitin
Sin Earring - (Green Frowning Mask), Stabilized Chaos
Shadow Ops agent's non-serial pistol - (copper revolver), Copper plating
Impatient partner - Element of Order + Spark of the Elder God + Bad-Fitting Dull Hat
Kunai Hisso - Tavena Sword + NetherRealm Magma + Necromancer Runestone
Battle license - Crypt Spider Silk + Gold Ore + Broken Trophy Remnants
Barbarian warrior face - Leather strap + Essence of Tarkatan's Rage + Battle Helmet
Transmute Coins (5000) - Gold Ore + Gold Ore + Copper Plating
Transmute Souls (250) - Essence of the Lost Soul + Essence of the Lost Soul + Necromancer Runestone
Life Shard (10) - Coagulated Vampiric Blood + Element of Order + Copper Plating
Silver dragon - Bottled Thunder + Obsidian Shard
Brute - Heart of the Dragon King + Nether Magic + Meteorite Dust
Gem of Nitara (10) - Coagulated Vampiric Blood + Cordite + Fragment of Order
Emergency radio Tekunin (10) - Worn Wiring + Carbon Film Resistor + Electrical Kit
The guide is out of date
If it's not difficult, tell me what exactly?